Have a good look at the little Suzuki DRZ400 a fine offroader and one suited to a first timer. It will do everything you want. Don't expect to much in terms of comfort though! It has a very narrow seat like a Cheese Wire!
KTM's are good bikes but too Exxxxxxpennnnnsive!
If you want something a bit bigger and more powerful than go for an allrounder - The best bike here is the Legendary and venerable YAMAHA XT600E or perhaps a newer version the XT660.
Triumph Bonneville 800 (2004), Yamaha XT600E (1999), Honda XBR500 (1986).